Method and apparatus for utilization of observable radiations



i i part of the spectrum.

n a beam o States, both residing at West Newton, l county of Middlesex, Commonwealth of A Maachusetts, have invented certain new and useful Improvements in Methods and .It lAp sratus for Utilization of Observable Ra iations, of which the following is a 10 specification.

Y This invention relates to signaling, observation and the like by rays ordinarily invisible, and is especially.adapted for use c `in war where operations are being conducted in the presence of the enemy. Our invention is founded upon the fact that there are radiations from a source of a high temperature such as an arc or inc andescent lamp at either side of the visible That is, of shorter and' longer wave lengths than the visible spectrum. The radiations at either side of t e visible spectrum while invisible them selves, follow generally the laws of redeci-, tion and refraction of visible light, and pro duce various tluorescent, chemical, electrical and other physical etl'ects which can be de- I A tected by suitable reeciying apparatus In car in out our invention w e project liysuc ravs to a distant point where it is collected, reflected or retracted for obq. servation.

Convenient apparatus i n accordance with our invention is set forth in the specification I :te which follows, and the saine illustrated in .A the accompanying drawings to which reference is made. In the drawings:

Figure 1 is a longitudinal sectional view offs combined receiving and transmitting sG-inrument in accordance with our inven- 8 isa transverse section of the saine n the line 2 2.

Fig. 3 a section similar to Fig. 1 but with lsl'parts removed and in fragment to'illustrate `adipstment for wide beam projection.

. 4 is a modified form of receiver and I -transmitter, and

' Fig. 5 is an end view of'the saine.

lo- There have been many diiculties in the utilization of radiation which by our invention have been avoided or overcome. Such difficulties are, for instance, the obtaini ing of a beam of suitable intensity from a if source practicable t'or use in the functions "herewfore stated; in the difficulty of pro normal -xaaiirnam. nm soins nu.. or weer m'ron, nssacrrusam muon normanna ron. vrxmzarxox or onsnvnna muriera.

riding receiving apparatus of sucient sensitiveness -without being at the saine time easily disarranged and uncertain of function; and above all providing both sending @o and receiving ap aratus suieientl portable for the practica operation of observation and signaling.

Many substances are extremely opaque to invisible rays or reflect them badly, and others, which are free from these diiculties, are practically unobtainable or unusable on a practical scale. For instance, quartz and iiuorspar are notoriousl transparent to ultraviolet, but neither o them can be had readily enough or in pieces of suicient size to render their use practicable. Rock salt, the substance most commonly used in the infra red portions of spectra on account of its great penneability to such rays, is ex- 15 tremely sensitive to moisture, and hence out of the question for military purposes.

To certain groups of invisible rays, which might otherwise be desirable, glass is quite opaque. and with certain others, refracting so substances are undesirable because theyabsorb badly. Moreover, certain groups of rays in themselves are undesirable for practical iisebecause they are quickly absorbed by the atmosphere, or are obtainable in ss quantity only from sources not convenient or general use. We have found therefore that each range. of invisible rays presents its specilic ditiiculty in generation, selection, sending and reception, and it is the object so of our invention to adapt each to each so as to produce a method and apparatus for the uti ization of invisible radiation of a simple, practical and eicient character.

The beam whether direct or reflected I6 should be suitably concentrated by reflection or refraction and may then be received upon devices possessing high sensitivene with respect to the particular group of radiations concemed. It may for instance be received upon a fluorescent screen and thereby made immediately optically visible.

We have found that, particularly for signaling purposes. a large part of the invisible range of radiations is ill adapted for one or the other of the reasons here suggested, and our preferred range of radiation for this purpose consists in those radiations lying between 400 up. and 350 pia wave length, which are just too short to be ordinarily visible to the human eye, and not et short enough to be suppressed by suite le we prefer a glass permeable for ra l oriordinary or redecting media.

radiations here referred to to isloate in practical quanbe screened out from the The up of 'il relatively easy tity, since it can rest of the spectrum by suitable vitreous colf' ered screens of relatively sim le character. We referably use a doub e screen of superim plates one takin out the blue 'and violet and one the red. or the former deeply colored with nickel s between 400 up and 350 up.

t which cuts o the visible spectrum down 'i t0 tbe red end. The other glass is a green copper glass quite permeable to the rays noted aa desired, but opaque to the red end I of the spectrum.

n' The ran of abeo lames slig tly overlap between 400 au and 350 ap..

tion of these two ut not in the band. The result is a maximum in the desired suppression with a i V"as th minimum eect on the desired transmission. i Furthermore, and of great practical imable use. xperimental work on ultraviolet radiations has been heretofore confined almost exclusively to sources especially rich in extreme ultra-violet, sources suc as highly specialized electric arcs, involving e use of iron or other metallic terminals, or by use of such sources as vacuum tubes and mercury arcs, poessing the same charl acteristics. 5 convenient for field use; most of them are unraising These sources are none of them steady and require the use of highly specia1- ized electrical sources involving voltage not readily obtainable of suicient strength in portable appliances.

The incandescent lamp also permits of an easy adjustment of range of the beam by or lowering the voltage of the current used. For short ranges or dark nights,

' tions and visibility is decreased by lowering the current while for longer ranges or brighter nights the lamp may be forced on a higher current. This is convenientl accomplished by cutting in extra cells in t e battery carried with the signal instruments as shown in Figbl.

especified grou we prefer to use is ree from these objecis of extremely low visibility. A vconcentrated beam of this character is comof radiations which pletely invisible in its passage through the I6 air, and invisible also to direct view beyond extremely short distances, compared with that atwhich it may be detected by means which we have provided and that meet all the practical requirements of an invisible signaling apparatus. In receiving such a -aaaeae 'Y beam,

it can be concentrated through glass lenses without serious loss of intensity,even non-achromatic lenses being 'suitable on account of the comparatively narrow range of wave lengths.

The fiuorescent eye piece'as' applied to spectroscopes out on a prism has long been known, but S far as we are aware no attem t has been made to produce a concentrate fluorescent image upon a fiuorescent screen of any kind for purposes herein described.

e have discovered moreover that the most reliable and sensitive fluorescent screens are radically dierent from those heretofore used in fluorescent eye pieces. We prefer to employ for this purpose translucent or opaque films of material 'ving a greenish uorescence when in a so 'd condition. We therefore use a translucent film of such material as barium platino cyanid deposited on some transparent material and viewed from the rear or compacted into an opaque screen and viewed from the front: upon which the light falls.

In order to make more clear the actual practice of our invention we have shown in the drawings as illustrative of means for practising our invention, certain apparatus adapted for field use.

For convenience in field work. we provide a combined ray projector and receiver adjustable for narrow or wide ray, which con sists of a suitable mounting, consisting of a tube 1, fitted with an ob'ective 2 and a movably mounted source of ight 3, pivoted at 4 within a bracket and normally held with ,its filament in the focus of the objective 2 by a s ring 6. (See Figs. 1 and 3.)

he lamp socket makes contact with a leaf 'i' insulated at 8, the other terminal being 1rounded in the mounting 1. The bracket is adjustably held in a slot 9 in the recessed wall l0 of n mounting section 11. When in the position shown in full lines in Fig. l, the filament of the incandescent lump 3 is in thc focus of the objective .2 and the circuit is closed. 'hen in the position indicated in dotted lines the circuit is broken.

The section 11 is slidable within the main mounting tube 1 and is adjiistiibly held by a slot and bolt at 12. At its forward end the section 11 has n front wall 13 in which is a central opening 14 in the axis of the objective 2.

Journaled near each of their ends in a renr wall and front wall 11 are rock shafts 15 and 16. The shaft 15 carries on a short arm, of proper length to cover the opening 14, a ray filter 1T for screening rays during receiving. The shaft 16 carries on a similar arm, a similar filter 18, but somewhat more dense, for use in sending. Both shafts are rocked by means of short handles 15 and 16t to throw the screens 17 and 18 into or in which the beam is spread ies 1 out of registry with the opening ltivelyiicreen the rays passin t rough it.

The aliding adjustment o the section 11 {1li-:imita the shifting of the filament of the p 3 relative to t e objective 2 in order to provide for a divergent, beam as illustrated in Fig. 3. This is sometimes dirable in ding in order to assist the receiving station to pick up the beam when it has not .10 been poible to get the instruments accurately alined.

Through the rear wall of the section 11 is alidingly fitted an eye piece tube 20 in a xed tube 21 fast in the rear wall and acting f. to ide and steady the eye piece tube.

' e tube 20 carries at its outer end a collar 22 extended upward to form a bearing for a rock shaft 23 which has on its outer end an arm 24.

, 1 0 The arm 24 carries the fluorescent screen which as above described is preferably a barium platino cyanid film up'on which the incident rays received produce a greenish uorescence. When in the sition shown in Fig. 1. the arm 24 is in its ateral position indicated in dotted lines in Fi 2. When the tube is pushed forward t e lower end of the collar 22 contracts with and pushes down the socket of the lamp 3. As the tube nears the vertical plane originally occupied by thelamp filament, the shaft 23 is rocked b reason of the travel of the pin 231 in the ot of the guide 23', xed on the rear plate v10. The movement of the tube 22 therefore not only removes the lamp but brings the tluorcent screen in the vertical plane of the focus of the objective and across its axis behind the opening 14. y i -Within the eye piece tube 20 is the eye '4 0 pieceroper 25 which with its lens cell 26 il hel by a screw in the wall 10. The eye -piece lens is therefore held at its proper point, the tube 20 being slotted to pass the screw in its longitudinal movement. D

45 The mounting 1 is carried on a trunnion mount 27, which again is rotatable in a horiaontal plane on its tripod 28. The mount section 11 is cut out at 29 to provide access to the lamp 3 for replacement.

The insulated spring 7 is connected up by a binding post 71 with a key 30 and battery 31 by a line 32 which is given electrical convnection to the mounting 1. When operating as a transmitter as shown u Fig. 1, the lamp filament is at the proper Lal length from the ob'ective 2 to give rejected parallel rays. en a divergent v beam is required the section 11 is pushed in and clamped as shown in Fig. 3. In each vi. case the heavy transmitter filter 18 is interm between lamp and objective and the "i as reduced to practical invisibility. The'light ao projected and screened is 'varied by interruption through a key 30 to produce intelligible signals which are re- 14 to selec#l I ceiving h pushing in the eye )iece slide 20. The sliile 20 in being pushed in turns ceived byA a similar instrument set'for rei down the lamp 3 to the position shown in dotted line in Fig. 1, the fluorescent screen at the same time being interposed as indicated so as to observably receive the concentrated rays focused by the objective.

Signaling in accordance with our invention may be successfully carried on over considerable distances and with practical safety from detection or observation. The devices described above as illustrative of our invention may be modified in various ways without departing from the spirit thereof as in the form shown in-Figs. 4 and 5.

In these figures the sender is independent of the receiver though preferably mounted to theron parallel axes.

n this form the sender consists of a tube fitted with an objective 31 and alined with the opening 32 of the casing 33. In this casing 33 we have shown a plurality of light sources 34 each similar to the sin (le lamp 3 shown in Fig. 1 and each capa le of being independentl moved to or from the focus of the objective 31. In this manner lamps may be quickly shifted without the delay of replacement or any break in signaling operation. Each lamp is pivoted at 35 and controlled at 36. The filter screen 3T is mounted within the tube 30 to cover or uncover the opening 32 as in Fig. 1.

In this form the sending objective 31 is smaller and the receivin objective 41 in its mounting considerably larger and focuses on afiuorescent screen 42 in an e epiece tube 44, which is slidably adjusta ile in the section 43. The pair as shown make a compactly mounting assembly while maintaining axial parallelism as shown in Fig. 5.

Both of these embodiments while practical and convenient may obviously be modified in form and structure and by the substitution of equivalent elements or parts, all without de arting from the spirit of our invention i within the limits of the appended claims.

'hat we therefore claim and desire to secure by Letters Patent is:

1. In signal apparatus of the class described. a combined projecting and receiving device comprisin an objective and an eye piece, a source o radiant energy and a fiuorescent medium both mounted in selective operative relation to said objective and a ray filter in inclusive association with said related parts.

2. A combined rojector and receiver of the class describe comprising a mounting, an objective set therein, a mounting section adjustable relative to said objective, a ray filter carried by said mounting section and adjustable therewith. an eye piece adjustab e in said mounting section, a source of 'A en of radiant energy and i: v. Al' ht 4"Elftor z" ai violet. rays,

etaprojector i ,'V". C 'vf .radiant ener and a uorescent medium each movable in selective relation to said objective.

3. A combined rojector and receiver of the clase describe com rising a mounting tube, an objective set t erein, a slide tube adjustable relative to said objective, a ray filter carried by said slide tube and adjustable therewith, an eye piece slidably adjustable in said mounting section, a source of '.1 radiant energy and a fluorescent medium each movable in selective relation to said I objective.

4. A combinetdeprojector and receiver `of the class descri comprising a mounting, .A an objective set therein, a mounting section ladjustable relative to said objective, an eye iece adjustable in said mounting section, a uorescent screen carried on the end o'f said eye piece, means for moving said screen into .and out of alinement with said eye piece upon the adjustment thereof, a lam mountf .ing pivoted in said section, means or yieldholding said mounting in the path of adjustment of said eye piece, a ray filter f movably carried on the forward end of said mounting, and means for changing the interceptive relation of the ray lter to said iobjective. Y

5. In a combined projector and receiver of the class described, anobjective, a source a fluorescent medium both mounted in selective operative relation Ato said objective and a plurality of ray filters, -one of said filters being movably mounted.

6. In a signal system, an incandescent bulb as a source of radiant energy, a excluding blue and violet rays but permitting the passage of ultra violet between 400 au. and 350 su, a second screen exclud- `ing the rays of the visible spectrum transmitted by the first screen by permitting the paage of the hereinbefore mentioned ultraa projector for directing the ht in a beam, a control for interrupting the light and a receiver including a screen -having a uorescence responsive to said ultra violet rays.

7. In a signal a oluding means beam of rays Y violet zone l l spectrum, an

le parat-us, a transmitter inor projecting a directed from that band in the ultrang next adjacent the visible a receiver including a screen lIl having a greenish fluorescence under said 8. In a signal system, a source of radiant having a vitreous inclosure, a filter inclu lng blue and violet rays but permitassage of ultra-violet between 400 up. O au, and a second screen excludin the rays of the visible spectrum transmit bythe screen by permitting the passage hereinbefore mentioned ultra-violet rays, for directing the light in a beam,

a control for interni image receiving screen avin a fluorescence responsive to said. ultra-vio et rays, a lens for focusing the received beam on said screen and eye p'iece for observing said screen.

9. An apparatus for observable utillization of invisible raya from that band in the ultra-violet zone lying next adjacent the visible spectrum and comprising a source of radiant energy, concentration, projection and ray selection devices operatively associated therewithfor the projection of the desired selected and directed beam, and an observational device including a fluorescent medium for collective visualization of the transmitted radiant energy.

10. A aratus for observable utilization of invisi e rays from that band in the ultraviolet zone lying next adjacent the visible spectrum and comprising an incandescent source of energy, a conoentrator for the beam thereof, a blue green filter, screen disposed in the th of said beam, means for predetermin lyY interrupting said beam, and an observation device adapted to be disposed in the path of said beam comprising a fluorescent screen, and an eye piece for observing the fluorescence of said screen under the action of said rays.

11. In a signal utilization of invisible rays from that band in the ultra violet zone lying next adjacent the visible spectrum, a sending and receiving device, a. projecting and receiving lens` an incandescent lamp movably mounted in said projector and positionable with its filament at the focus of said lens, a fluorescent screen movably mounted in said in interchangeable relation to said ment at said focus, an eye piece focusable upon the image of said lens, and a ray filter removably mounted in the axis of said projector.I l l md 12. n a si system em ovin p etermined radigiilions of low gisibiliiy from that band in the ultra-violet zone lying next adjacent the visible spectrum, a receiver consisting of means for concentrating such transmitted predetermined radiations, a fluorescent screen at the point of concentration sensitive to such radiations. a filter cover for said screen excluding all but the predetermined radiations of said transmitted beam and an eye piece mounted for vobaervations of said fluorescent screen.

13. In a signal system for observable utilization of invisible ra 's from that band in the ultra violet zone ying adjacent the visible spectrum, a sender and a receiver, pro'ecting and receiving instrumentality inclu ing an incandescent lamp operatively mounted for projection, a fluorescent screen o ratively mounted for receiving, an eye piece focusable upon the image of said lens lamp filatheiigiit, airV system for observable projector l v .iftermined radiations of low visi l thst band in the ultra-violet zone lying adproiection. 14. In s signal system emploing predeility from jacent the visible spectrum, a receiver consisting of s lens for concentrating such l., devise, s projecting and receiving transmitted predetermined radiations, a .uorescent screen at the focus of said j 1a lem and sensitive to such radiations, a

filter for said screen and excluding all but the predetermined radiations of said transmitted beam and an eye piece mounted for observation of said fluorescent screen.

15. In a signal system, a sending and re- =on filter "the sxis of lens, an incandenscent lamp movabl mounted in said projector and positions le with its filament at the focus of said lens, a fluorescent screen movabl mounted in said 20 rojector in interchangea le relation to said amp at said focus, s stronger ray filter movably mounted in the optical axis of said device, and a weaker ray filter movably mounted in said axis.

In testimony whereof we aix our signatures in presence of two witnesses.

NORMAN MARSHALL. v LOUIS BELL.

Witnesses:

Vlcronm Lownnx, Gnomiz B. RAwuNos. 

